Irreversibility and Singularities

by Bérengère Dubrulle (SPEC, CNRS, CEA Saclay, Université Paris-Saclay)

Wednesday 21 Apr 2021, 14:30 → 16:00 Europe/Rome

In a viscous fluid, the energy dissipation is the signature of the breaking of the time-reversal symmetry (hereafter TSB). In the limit of large Reynolds numbers, the non-dimensional energy dissipation per unit mass becomes independent of the viscosity, meaning that the time-reversal symmetry is spontaneously broken.  I show that the TS breaking is akin to a spontaneous phase transition in the Reversible Navier- Stokes equations, suggested by Gallavotti. I then discuss the mechanism of the TSB in Navier-Stokes via quasi-singularities that create a non-viscous dissipation and exhibit the tools to track them. I apply them to experimental velocity measurements in a turbulent von Karman flow.

Link per il collegamento: https://meet.google.com/pip-kvzt-fkz